BEIRUT (AP) -- Shells hit the center of a Syrian Kurdish enclave on Tuesday where Turkey is carrying out an offensive, landing near the area's only hospital and killing one person, the hospital manager and a monitoring group said.

The shelling near Afrin hospital is the first time the district's center has been targeted since Turkey began its offensive, now in its fourth week. It left two civilians seriously injured.

Turkey has sent in troops, lobbed artillery from across the border and used airstrikes in its operation in the Afrin enclave to rout the Syrian Kurdish militia, known as the People's Defense Units or the YPG. Ankara has also backed thousands of Syrian local fighters who are taking part in its ground operation in Afrin.

Turkey considers the YPG to be a "terrorist" group, but the group is backed by the U.S. and forms the backbone of the internationally backed Syrian Democratic Forces fighting Islamic State militants in Syria.

The Afrin offensive has further deepened tensions between Turkey and the U.S. over Washington's support of the Kurdish militia. The operation began Jan. 20, and has been met with stiff resistance from the YPG. The operation has mostly focused on Afrin's western, eastern and northern areas.

Jiwan Mohamed, the Afrin hospital manager, said for the first time since Jan. 20, shells landed in the town's center, including one only 50 meters (yards) from the hospital on Tuesday. One taxi driver bringing in wounded was killed and five others were injured, including two critically, Mohamed said.

Mohamed said the attack disrupted baby deliveries, cut an electricity cable feeding one hospital section and sent panicked patients and staff to the streets.

Two other shells, which he said came from the Turkey-backed forces in the east, landed in other parts of Afrin town.

The Syrian Observatory for Human Rights said the shell that landed near the hospital entrance killed one person. The violence also killed two women in Afrin enclave Tuesday, the Observatory said. Tuesday's deaths bring the total casualties since Jan. 20 to 77, including 21 children and 15 women, according to the Observatory.

Mohamed puts the death toll much higher, saying his hospital records show at least 157 civilians have died in the offensive, while over 400 were wounded. The discrepancy couldn't be immediately reconciled.

Turkey says at least 31 of its soldiers were killed in the operation so far.